Why are some virtual machines orphaned after rebooting a High Availability (HA) enabled host?

A.
The Orphaned virtual machines have HA restart disabled.

B.
The Orphaned virtual machines moved recently and the change did not persist.

C.
The host is attached to failed storage.

D.
The host just came out of maintenance mode.

Explanation:
If the host is rebooted within an hour after the virtual machines are moved or powered on, the vmInventory.xml file does not persist and hostd does not report these
virtual machines as registered on the host. In an HA-enabled cluster, this condition impacts only the virtual machines with HA restart disabled.
https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003742#reboothostonehour